There has been known a fuel injection device including a control body, which has a pressure control chamber, and a valve member for opening and closing a valve portion in response to the pressure of fuel in the pressure control chamber. In the fuel injection device, the pressure control chamber of the control body has an inflow port and an outflow port opened therein. The inflow port is a port through which fuel flowing through a supply channel flows into the pressure control chamber, and the outflow port is a port through which the fuel is discharged to a return channel. The pressure of the fuel in the pressure control chamber is controlled by a pressure control valve for making communication between the outflow port and the return channel and for interrupting the communication between them.
In the fuel injection device, a valve member opens and closes a valve portion in accordance with a variation of the fuel pressure in the pressure control chamber. Therefore, it is preferable to rapidly increase or decrease the fuel pressure in the fuel control chamber, with respect to a switch operation between the communication of the outflow port and the return channel, and the interruption of the communication. In a fuel injection device disclosed in a patent document 1 (EP Patent No. 1656498), a pressing member is further provided in a pressure control chamber, to be reciprocally displaced in the pressure control chamber. When the outflow port is made to communicate with the return channel by the pressure control valve, the pressing member is drawn to the abutting surface having the outflow port opened therein by the flow of the fuel flowing to the outflow port from the pressure control chamber, thereby pressing the abutting surface by a pressing surface of the pressing member. When the communication of the inflow port, the pressure control chamber and the outflow port is interrupted by the pressing member pressed to the abutting surface, the pressure of the fuel in the pressure control chamber is rapidly decreased.
When the communication between the outflow port and the return channel are interrupted by the pressure control valve, the pressing member receives pressure in a direction to separate the pressing surface from the abutting surface by the flow of the fuel flowing into the pressure control chamber from the inflow port. When the inflow port, the pressure control chamber and the outflow port are brought into the state of communication by the displacement of the pressing member, the pressure of the fuel in the pressure control chamber is rapidly increased.
As described above, the pressing member displaces to be reciprocated in accordance with the switch operation of the pressure control valve between the communication of the outflow port and the return channel, and the interruption thereof. Therefore, it is possible to rapidly increase or decrease the fuel pressure in the pressure control chamber.
In the fuel injection device disclosed in the patent document 1, the pressing member movable in the pressure control chamber may contact an inner wall surface of a control body, which encloses the abutting surface exposed to the pressure control chamber. If an outer wall surface of the pressing member contacts an inner wall surface of the control body, the fuel cannot be normally held between the outer wall surface of the pressing member and the inner wall surface of the control body at the contact portion. In this case, the outer wall surface of the pressing member may be pressed to the inner wall surface of the control body, due to the fuel pressure in the pressure control chamber. Thus, it may be difficult for the pressing member to be smoothly reciprocated in the pressure control chamber, and thereby response of the pressure control valve for switching between the communication of the outflow port and the return channel, and the interruption thereof may be deteriorated.